1. Field
Aspects of the present disclosure relate to wireless local area network (WLAN) communications, and more particularly to rate adaptation for Wi-Fi based wireless sensor devices.
2. Background
Current rate selection algorithms in Wi-Fi systems are geared to select the appropriate transmission rates for devices that are always on, and can therefore rely on a constant stream of metrics (CINR, SSID, Packet Error rate, throughput, etc.) measured on data constantly transmitted by those devices.
This type of scenario, however, is not the scenario under which low power Wi-Fi sensor devices will operate. Wi-Fi-based sensors will remain with their radios turned off for large amounts of time and only wake up at the moments they are due to transmit sensor data in order to limit their current consumption and thus extend their battery lifetimes. For example, a Wi-Fi sensor might turn off its radio for a period of 5 minutes and then turn it on for only a few hundreds of milliseconds to transmit data.
Because Wi-Fi-based sensors turn on their radio for short amounts of time, the amount of performance metrics they gather may be limited. For example, the Wi-Fi-based sensor may only have a small amount of time prior to a time the Wi-Fi-based sensor transmits data to be able to gather information regarding the current state of the channel. Further, the performance metrics gathered by the Wi-Fi-based sensor may not be current or stale with respect to a standard configuration. Indeed, if the Wi-Fi-based sensor uses information of regarding the state of the channel that is gathered by the Wi-Fi-based sensor prior to turning off its radio, that information could have been gathered at a time far back in the past (minutes or even hours) compared to the time at which the sensor turns on its radio one more time to transmit data.
As a result, the typical Wi-Fi rate selection algorithms, designed for traditional always-on radios very poorly suited for usage for Wi-Fi-based sensor applications.